The invention relates to an electric toothbrush with a hand-held handle component, with a motor and drive mechanism, and a brush attachment, which has several rotatable tufts of bristles, fastened to said handle component. Said tufts are driven by a transmission built into said brush attachment. The drive mechanism is designed in such a way that, in addition to a rotational movement of the bristle tufts, it also creates an oscillating movement of the brush attachment about its longitudinal axis.
Such a toothbrush is the subject of U.S. Pat. No. 4,989,287 which issued on Feb. 5, 1991 and is of common ownership with the present application, and which is incorporated herein by reference. In this known toothbrush, the brush attachment can be oscillated about its longitudinal axis by means of a secure coupling link with which it is attached to the forward part of the handle component's casing. The transmission mechanism is designed as a non-rotating connecting rod within the brush attachment, wherein said connecting rod can create an oscillating movement about its longitudinal axis and a back-and-forth movement in the direction of its longitudinal axis by means of an oscillating crank and an eccentric that engages said crank. The back-and-forth movement of the connecting rod is transformed in the bristle head of the brush attachment to a rotational movement of the bristle tufts while the oscillating movement of the connecting rod creates a corresponding oscillation of the entire brush attachment.
Movement of the bristle tufts by means of a connecting rod is relatively expensive, and the connecting rod presents a problem if one wants to increase the angle at which the individual bristle tufts oscillate. Further, it is impossible to continuously rotate the bristle tufts in one rotational direction using a connecting rod.
Electric toothbrushes have also become known in which the bristle tufts are driven by a shaft instead of a connecting rod. US-A-2 215 031 and DE-A-34 06 112 are examples of this state of the art. However, in both of these toothbrushes, the part that holds the bristle tufts of the toothbrush cannot be moved by the motor of the toothbrush relative to the handle component.